Development of herbicide-tolerant lines through marker assisted backcross breeding

The widespread adoption of direct-seeded rice cultivation over traditional puddled transplanted rice has become necessary due to labor shortages and water scarcity. Amidst several biotic and abiotic challenges faced by direct seeded rice cultivation, weeds remain as a major bottleneck which negatively influences the performance of rice crop. Chemical method of weed control is one of the most economical ways compared to other weed management techniques. Development of rice lines which are resistant to new classes of broad-spectrum herbicides have paved way to introduce them into direct seeded rice cultivation. In this study, the herbicide-tolerant mutant named Robin-HTM, developed at Tamil Nadu Agricultural University and tolerance to imazethapyr, was used as a donor parent to introgress herbicide tolerant into the popular rice variety ADT 43. Initial evaluation with herbicide was done with the parents alone and subsequent evaluation was done in the advance backcross progenies of ADT 43 x HTM cross. The promising lines which perform better than the recurrent parent is selected and forwarded through backcrossing. Weed related parameters were also calculated in this study, to understand the weed dynamics present and the efficiency of the herbicide used.